Stamp is scaled

[Mark0ne]

When using page.merge_page(wmPage, over=True) to apply a stamp, the stamp is scaled

Environment

Windows 10 x64, Python 3.10 x64

$ python -m platform
Windows-10-10.0.19045-SP0

$ python -c "import pypdf;print(pypdf._debug_versions)"
pypdf==3.16.2, crypt_provider=('local_crypt_fallback', '0.0.0'), PIL=9.0.1

Code

from pypdf import PdfWriter, PdfReader, Transformation
from os import remove as fileDelete
import os.path

OUT_PATH = r"TMP_OUT.pdf" #Path
SRC_PAGE = r"PAGE.pdf"
WM_PAGE = r"PDF_WATERMARK.pdf"

if __name__=="__main__":
    pdfOut = PdfWriter() #Blank writer
    pdfOut.append(SRC_PAGE)
    
    wmPage = PdfReader(WM_PAGE).pages[0]
    for page in pdfOut.pages:
        page.merge_page(wmPage, over=True) #False (watermark does not seem to mirror.)

    if os.path.exists(OUT_PATH):
            fileDelete(OUT_PATH)
    pdfOut.write(OUT_PATH)
    pdfOut.close()

Problems

I've not fully diagnosed, but it looks like if the WM_PAGE is a different resolution (DPI) then it appears at a different scaling. This is perhaps less of an issue, but would appreciate some tips to correct it.

[stefan6419846]

• Please check whether 3.16.2 fixes this, as there has been a recent change.
• You might want to call page.transfer_rotation_to_content before the merge as documented. Do you still see this behavior?

If both approaches do not work, please provide corresponding PDF files for further analysis.

[Mark0ne]

Thanks.
3.16.2 does fix the mirror issue. I'm still left with the scaling issue. I'm pretty sure this is related to document resolution mismatch.....I'll spend some more time debugging and report my findings.

[Mark0ne]

Scaling issue solved with

pageRect = pdfOut.pages[0].mediabox
wmPage.scale_to(pageRect.width,pageRect.height)

Many thanks all solved and no issue.

[MartinThoma]

I've edited the title and the top post as the mirroring-issue is already fixed and documented via #2191 and fixed via #2203 in pypdf>=3.16.2

[MartinThoma]

Oh, nice!

So was it related to different resultions?

[Mark0ne]

I believe it was:

• two pages from the same source will appear at the same scale (when one is stamped over the other).
• the watermark page I'm using was created in GIMP for windows. It has reduced resolution DPI (72 or 100...can't recall right now).

So fast compared to the previous version of pypdf I was using. Some huge improvements! Many thanks